1. Field of the Invention
The present invention relates to an optical element drive mechanism suitable for use in an image pickup apparatus with a bending optical system, and relates to an image pickup apparatus having the optical element drive mechanism.
2. Description of the Related Art
An image pickup apparatuses is generally demanded to have a telephoto lens or a zoom lens and have an ability of compactly storing a lens barrel at non-photographing time for ease of handling and transport of the apparatus.
To this end, some image pickup apparatus has a bending optical system including a reflection optical element (e.g., a prism) disposed between object-side and image-side lens groups, the object-side lens group being attached to an expandable and retractable barrel and the image-side lens group being used for forming an image on an image pickup element disposed within an apparatus main body.
Another image pickup apparatus with a bending optical system has been proposed, in which a lens barrel is retracted into an empty space created by moving a reflection optical element to a retract position, whereby the lens barrel is stored inside an apparatus main body (see, Japanese Patent No. 4028721, for example).
The proposed image pickup apparatus includes a lens frame that retains a lens group into which a light flux incoming from an object is incident along a first optical axis. The lens frame is movable along the first optical axis between a use position where the frame is projected from a housing and a storage position where the frame is retracted into the housing. The image pickup apparatus further includes a prism for bending the light flux passing through the lens group from the first optical axis to a second optical axis crossing therewith, thereby projecting the light flux onto an image pickup element. To ensure a space for receiving the lens frame, the prism is retracted along the second optical axis from a position where the prism guides the light flux passing through the lens group to the image pickup element to a retract position where the prism is on the side of the image pickup element.
Still another image pickup apparatus has been proposed that has a reflection optical element configured to be retracted when a camera is in a storage state (see, for example, Japanese Laid-open Patent Publication No. 2006-259685). This image pickup apparatus includes an image pickup optical system, retained by the lens barrel, for forming an optical image of an object. The image pickup optical system includes an object-side lens group to which light beams from the object are incident, and a reflection optical element having a reflection surface for bending light beams output from the object-side lens group. When the camera is in an image pickup state, the object-side lens group is held to be movable in the direction of light beams incident from the object. When the camera is in the storage state, the reflection optical element is retracted to a retract position different from a position disposed when the camera is in the image pickup state.
However, in the image pickup apparatus disclosed in Japanese Patent No. 4028721, the lens group for receiving the light flux incident from the object along the first optical axis is supported by guide shafts. At the time of photographing, the lens group is set at a position where it projects from a camera main body. Due to the support structure for the lens group, it is difficult to project the lens group beyond a certain amount, resulting in a problem that the lens group is not suitable for use in a high-powered zoom optical system.
Japanese Laid-open Patent Publication No. 2006-259685 discloses establishing the storage state of the camera by retreating the reflection optical element to a retreat position different from its position disposed when the camera is in the image pickup state, but fails to disclose a concrete construction for establishing the storage state.